This invention relates generally to inflatable passive restraint systems for use in vehicles for restraining the movement of a seated occupant such as in the event of a collision and, more particularly, to improved assemblies and methods for housing, positioning or attaching either or both a gas generator and an inflatable bag in a vehicle.
It is well known to protect a vehicle occupant by means of safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e., "passive restraint systems." Such systems commonly contain or include an inflatable vehicle occupant restraint, such as in the form of a cushion or bag, commonly referred to as an "airbag cushion." In practice, such airbag cushions are typically designed to inflate or expand with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such an airbag cushion may desirably deploy into a location within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, instrument panel or the like, to prevent or avoid the occupant from forcibly striking such parts of the vehicle interior.
Generally, it is common to utilize airbag module assemblies which include a combination or assembly of at least three basic components: 1) a cushion or airbag that is inflated with gas such as when the vehicle encounters a sudden deceleration, 2) a gas generator, also commonly referred to as an "inflator," which upon actuation serves to provide the gas used to inflate the airbag cushion, and 3) a reaction canister which typically functions as a structural housing supporting either or, typically more desirably, both the inflator and the airbag cushion while providing a mounting base for installation of the assembly in a vehicle and directing inflation gases resulting from the inflator into an associated airbag cushion.
Such reaction canister housing structures are typically in the form of an open-mouthed container, formed with a body portion, such as composed by one or more body parts, and with an end plate fastened at each opposed end of the container body portion. Usually, the airbag cushion, in an uninflated and folded condition, is placed into and housed within such an open-mouth reaction canister housing.
In practice, reaction canister housings which contain an airbag cushion for the protection of a front seat passenger commonly form an opening wherethrough the airbag cushion is deployable which is generally rectangular in cross sectional shaped. Normally, a passenger side airbag module assembly is mounted in or closely behind what is called the vehicle instrument panel or dashboard (hereinafter referred to as the "instrument panel"), with the airbag deployment opening of the reaction canister generally positioned planar or adjacent with the instrument panel. In the case of a driver side module installation, a corresponding driver side assembly combination is typically housed in or secured to the steering wheel.
In addition to providing a protective housing for the inflator and the airbag cushion until the time of deployment of the latter, such a housing structure can also desirably act to absorb the loads generated by or associated with the deployment of the associated airbag cushion. Typically, these loads are large and unless sufficiently and properly absorbed can cause damage to the vehicle including, in the case of a passenger side assembly, damage to the instrument panel.
Many past and present airbag module designs utilize relatively low-cost stamped steel as a basic housing component material of construction. The strength of such steel-fabricated structures can be tailored to the needs of particular system installations. For example, by varying the thickness of steel utilized therein, damage due to the impact of deployment loads can be minimized or avoided.
Emphasis on weight reduction in automobiles has, however, resulted in a strong interest in lighter weight inflatable passive restraint systems. A significant reduction in the weight of a passenger side passive restraint system can be achieved through the utilization of aluminum rather than a heavy steel material, as used in previous reaction canister housing structures. Thus, even though aluminum is generally more costly than steel, the lighter weight of aluminum has lead to the greater use thereof in reaction housing assembly and design.
Also, as shown in various commonly assigned U.S. Patents including, for example: Lauritzen et al., U.S. Pat. No. 5,332,256, issued Jul. 26, 1994; Lauritzen et al., U.S. Pat. No. 5,344,182, issued Sep. 6, 1994; Lauritzen et al., U.S. Pat. No. 5,395,133, issued Mar. 7, 1995; Lauritzen et al., U.S. Pat. No. 5,407,226, issued Apr. 18, 1995 and Lauritzen et al., U.S. Pat. No. 5,407,227, issued Apr. 18, 1995, the disclosures of which patents are incorporated herein by reference in their entirety, housing structures such as formed of aluminum are well suited for fabrication by extrusion techniques. As disclosed in such patents, such extrusion fabrication techniques permit or allow the incorporation of cushion attachment channels, slots, sleeves or the like in the housing structure, the use of which permits the attachment or holding of an airbag cushion within the housing structure while reducing or minimizing the number of required fasteners.
Thus, although sheet steel generally costs significantly less than aluminum, prior art steel-based housing designs have typically required separate components for cushion attachment, such as retainer tubes, brackets, fasteners or rods to be incorporated or used in conjunction therewith. As will be appreciated, the inclusion of such additional components can and typically do significantly increase assembly cost and weight.
In practice, the component parts of prior art inflatable restraint assemblies, e.g., the reaction canister body and corresponding end plates, even in those assemblies wherein the reaction canister housing is formed of extruded aluminum, are typically joined and held together through the use of a plurality of selected fasteners such as screws, rivets or bolts. For example, a selected fastener is typically passed through fastener holes which have been preformed in the respective parts to be fastened together. Such fastener holes commonly take the form of screw channels, such as formed during extrusion processing or otherwise, in or along the reaction canister body. Further, it is relatively common for reaction canister assemblies to rely on the inclusion and use of a plurality of fasteners in order for the reaction canister assembly to maintain needed or desired structural stability upon deployment of the associated airbag cushion, particularly at or near the chute or mouth portion of the reaction canister assembly wherethrough, upon proper actuation, the airbag cushion is deployed and the impact of the deployment forces can be especially pronounced.
The manufacture and production of assemblies that utilize multiple fasteners typically require additional production or process machinery and associated operating personnel. For example, facilities for the production of such assemblies which require multiple fasteners commonly include multiple fixture devices to effect and maintain proper fastener hole alignment for insertion of a fastener as well as a selected form or forms of driver devices in order to drive each fastener into the corresponding fastener hole alignment. Such additional production steps may undesirably slow the assembly process and increase the costs associated with such assemblies.
Furthermore, each fastener is an entity in and of itself with each such fastener needing to be secured and tightened to a specific torque, thereby complicating the assembly process. Also, in order to better ensure safe and proper operation of an airbag module assembly, the component parts of the assembly and typically including each fastener, as well as the particulars of each such component, is desirably recorded and tracked. Such recording and tracking operations, however, can become undesirably complicated and burdensome as the number of component parts required for a particular assembly design is increased. In view thereof, airbag module assemblies are generally preferably designed to minimize the number of component parts used therein.
In contrast to extruded housing designs, steel-based designs typically require costly multiple spot welds or the use of mechanical joining techniques to construct the general module housing structure. Further, one or more costly plating or coating operations is commonly required following such spot weld joinder.
To make vehicular inflatable restraint systems more affordable and thus the benefits attendant the installation of such systems more widely realizable, airbag module suppliers and manufacturers are faced with the ongoing mission to reduce and minimize costs.
In view of the above, there is a need and a demand for an airbag module assembly design which reduces or minimizes costs such as by one or more of the following:
1) permitting the more widespread use of low-cost stamped steel rather than aluminum housings,
2) permitting or facilitating fast and/or simplified assembly of such module assemblies or subassemblies such as by permitting airbag cushion attachment without requiring the use of numerous separate fastener components, by avoiding the need for costly spot welds or mechanical joining methods to construct a module housing of stamped steel and by avoiding the need for post-spot welding plating or coating operations,
3) better ensuring the secure attachment of an airbag cushion in an associated housing device, and
4) permitting the more widespread common use of assembly or housing sections or portions in various module or assembly designs.